Poly(hydroxy ether)s, also known as phenoxy resins, are linear polymers typically prepared by copolymerization of 2,2-bis(4 hydroxyphenyl)propane (bisphenol A) with 2,2-bis(4-hydroxyphenyl)propane-epichlorohydrin polymers (epoxy resins). Phenoxy resins contain about 6 percent by weight secondary alcohol groups.
Phenoxy resins are used to enhance the properties of coating, adhesive, ink, composite, fiber, and plastic compositions. The pendant hydroxy groups and backbone ether linkages promote wetting and bonding to polar substrates, pigments, and fillers. The addition of phenoxy resin to thermoplastics can help control process rheology in extrusion, molding, and film-forming operations. The amorphous nature of phenoxy resins can be helpful in controlling the crystallization kinetics of crystalline and semicrystalline thermoplastic materials.
Phenoxy resins have excellent compatibility with polar polymers, such as polyesters, polycarbonates, polyamides, and polyurethanes. However, phenoxy resins have low compatibility with polystyrene, poly(phenylene ether), polyolefins, (meth)acrylics and other non-polar polymers. The low compatibility of phenoxy resins with non-polar polymers limits their usefulness as additives for non-polar polymers, as compatibilizing agents for blends of polar and non-polar polymers, and as compatibilizing agents for blends of non-polar polymers and polar fillers.